I. Field of the Invention
The present invention relates generally to filter assemblies and, more particularly, a return line filter assembly which is at least partially submerged in a fluid reservoir.
II. Description of the Prior Art
There have been a number of previously known return line filters adapted for connection with a fluid system and, particularly, hydraulic systems. Such return line filters typically comprise a housing at least partially submerged within a fluid reservoir while a filter element is positioned within the interior of the housing. A fluid inlet on the housing is fluidly connected to the return line from the fluid system while passage means formed through the housing connect the inlet to one side of the filter element. Fluid flow into the housing inlet thus flows through the fluid passage means and through the filter so that the filtered fluid enters the fluid reservoir.
These previously known return line filters, however, have all suffered from a number of disadvantages. One disadvantage of many of the previously known return line filters is that the filter element could not be removed for cleaning or replacement without shutting down the entire fluid system. This is particularly disadvantageous when frequent changes of the filter element are required.
A still further disadvantage of many of these previously known filter assemblies is that the filter assemblies were often operated during the inadvertent or even intentional omission of a filter element from the filter assembly. The omission of the filter element, of course, enabled debris and other foreign matter to undesirably enter the fluid system. Moreover, detection of omitted filter elements required the opening of the housing for visual inspection of the filter element.
A still further disadvantage of many of these previously known return line filter assemblies is that removal of the filter element from the filter assembly in turn undesirably removed a portion of the fluid from the reservoir due to the suction of the filter element. This removed fluid oftentimes splashed on the floor and created an undesirable and unsafe working environment.
A still further disadvantage of many of these previously known return line filters is that splashing of the fluid during either the filtering operation or, alternatively, when the filter element was removed from the housing, oftentimes introduced air bubbles into the fluid. Such air bubbles can enter the fluid system and adversely affect the operating efficiency of the system. Moreover, in the case of a hydraulic system, such air bubbles can cause pump cavitation and even create air pockets within the hydraulic system.